summaryrefslogtreecommitdiffstats
path: root/fs/notify/group.c
diff options
context:
space:
mode:
Diffstat (limited to 'fs/notify/group.c')
-rw-r--r--fs/notify/group.c171
1 files changed, 171 insertions, 0 deletions
diff --git a/fs/notify/group.c b/fs/notify/group.c
new file mode 100644
index 000000000..1de6631a3
--- /dev/null
+++ b/fs/notify/group.c
@@ -0,0 +1,171 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * Copyright (C) 2008 Red Hat, Inc., Eric Paris <eparis@redhat.com>
+ */
+
+#include <linux/list.h>
+#include <linux/mutex.h>
+#include <linux/slab.h>
+#include <linux/srcu.h>
+#include <linux/rculist.h>
+#include <linux/wait.h>
+#include <linux/memcontrol.h>
+
+#include <linux/fsnotify_backend.h>
+#include "fsnotify.h"
+
+#include <linux/atomic.h>
+
+/*
+ * Final freeing of a group
+ */
+static void fsnotify_final_destroy_group(struct fsnotify_group *group)
+{
+ if (group->ops->free_group_priv)
+ group->ops->free_group_priv(group);
+
+ mem_cgroup_put(group->memcg);
+ mutex_destroy(&group->mark_mutex);
+
+ kfree(group);
+}
+
+/*
+ * Stop queueing new events for this group. Once this function returns
+ * fsnotify_add_event() will not add any new events to the group's queue.
+ */
+void fsnotify_group_stop_queueing(struct fsnotify_group *group)
+{
+ spin_lock(&group->notification_lock);
+ group->shutdown = true;
+ spin_unlock(&group->notification_lock);
+}
+
+/*
+ * Trying to get rid of a group. Remove all marks, flush all events and release
+ * the group reference.
+ * Note that another thread calling fsnotify_clear_marks_by_group() may still
+ * hold a ref to the group.
+ */
+void fsnotify_destroy_group(struct fsnotify_group *group)
+{
+ /*
+ * Stop queueing new events. The code below is careful enough to not
+ * require this but fanotify needs to stop queuing events even before
+ * fsnotify_destroy_group() is called and this makes the other callers
+ * of fsnotify_destroy_group() to see the same behavior.
+ */
+ fsnotify_group_stop_queueing(group);
+
+ /* Clear all marks for this group and queue them for destruction */
+ fsnotify_clear_marks_by_group(group, FSNOTIFY_OBJ_TYPE_ANY);
+
+ /*
+ * Some marks can still be pinned when waiting for response from
+ * userspace. Wait for those now. fsnotify_prepare_user_wait() will
+ * not succeed now so this wait is race-free.
+ */
+ wait_event(group->notification_waitq, !atomic_read(&group->user_waits));
+
+ /*
+ * Wait until all marks get really destroyed. We could actually destroy
+ * them ourselves instead of waiting for worker to do it, however that
+ * would be racy as worker can already be processing some marks before
+ * we even entered fsnotify_destroy_group().
+ */
+ fsnotify_wait_marks_destroyed();
+
+ /*
+ * Since we have waited for fsnotify_mark_srcu in
+ * fsnotify_mark_destroy_list() there can be no outstanding event
+ * notification against this group. So clearing the notification queue
+ * of all events is reliable now.
+ */
+ fsnotify_flush_notify(group);
+
+ /*
+ * Destroy overflow event (we cannot use fsnotify_destroy_event() as
+ * that deliberately ignores overflow events.
+ */
+ if (group->overflow_event)
+ group->ops->free_event(group, group->overflow_event);
+
+ fsnotify_put_group(group);
+}
+
+/*
+ * Get reference to a group.
+ */
+void fsnotify_get_group(struct fsnotify_group *group)
+{
+ refcount_inc(&group->refcnt);
+}
+
+/*
+ * Drop a reference to a group. Free it if it's through.
+ */
+void fsnotify_put_group(struct fsnotify_group *group)
+{
+ if (refcount_dec_and_test(&group->refcnt))
+ fsnotify_final_destroy_group(group);
+}
+EXPORT_SYMBOL_GPL(fsnotify_put_group);
+
+static struct fsnotify_group *__fsnotify_alloc_group(
+ const struct fsnotify_ops *ops,
+ int flags, gfp_t gfp)
+{
+ static struct lock_class_key nofs_marks_lock;
+ struct fsnotify_group *group;
+
+ group = kzalloc(sizeof(struct fsnotify_group), gfp);
+ if (!group)
+ return ERR_PTR(-ENOMEM);
+
+ /* set to 0 when there a no external references to this group */
+ refcount_set(&group->refcnt, 1);
+ atomic_set(&group->user_waits, 0);
+
+ spin_lock_init(&group->notification_lock);
+ INIT_LIST_HEAD(&group->notification_list);
+ init_waitqueue_head(&group->notification_waitq);
+ group->max_events = UINT_MAX;
+
+ mutex_init(&group->mark_mutex);
+ INIT_LIST_HEAD(&group->marks_list);
+
+ group->ops = ops;
+ group->flags = flags;
+ /*
+ * For most backends, eviction of inode with a mark is not expected,
+ * because marks hold a refcount on the inode against eviction.
+ *
+ * Use a different lockdep class for groups that support evictable
+ * inode marks, because with evictable marks, mark_mutex is NOT
+ * fs-reclaim safe - the mutex is taken when evicting inodes.
+ */
+ if (flags & FSNOTIFY_GROUP_NOFS)
+ lockdep_set_class(&group->mark_mutex, &nofs_marks_lock);
+
+ return group;
+}
+
+/*
+ * Create a new fsnotify_group and hold a reference for the group returned.
+ */
+struct fsnotify_group *fsnotify_alloc_group(const struct fsnotify_ops *ops,
+ int flags)
+{
+ gfp_t gfp = (flags & FSNOTIFY_GROUP_USER) ? GFP_KERNEL_ACCOUNT :
+ GFP_KERNEL;
+
+ return __fsnotify_alloc_group(ops, flags, gfp);
+}
+EXPORT_SYMBOL_GPL(fsnotify_alloc_group);
+
+int fsnotify_fasync(int fd, struct file *file, int on)
+{
+ struct fsnotify_group *group = file->private_data;
+
+ return fasync_helper(fd, file, on, &group->fsn_fa) >= 0 ? 0 : -EIO;
+}